Which layer of the OSI model is Modbus TCP encapsulated in?

Modbus TCP is an industrial communication protocol that operates over TCP/IP networks. It is primarily encapsulated within the Application Layer of the OSI model. This is because Modbus focuses on the messaging structure and the types of operations, such as commands and responses, that can be performed between devices in a network.

In the context of the OSI model, the Application Layer is responsible for providing services directly to end-user applications, including various protocols like HTTP, FTP, and Modbus TCP. When using Modbus TCP, the protocol defines how data is packaged and exchanged between devices that communicate over a TCP/IP network, reflecting a typical use case of the Application Layer handling the logic of the application-level communication.

The other layers of the OSI model serve different purposes. The Transport Layer is responsible for ensuring complete data transfer and managing the flow of data between systems. The Network Layer is responsible for routing the data packets across the network, while the Data Link Layer deals with the physical transmission of data over a medium, which is not specific to the content or structure of the messages themselves as dealt with in the Application Layer. Therefore, identifying Modbus TCP as an Application Layer protocol properly situates it within the framework of the OSI model.